the oppostie of red is cyan
the opposite of green is magenta
the opposite of blue is yellow

those three relationships are CRITICAL to understand no matter whether your working in a "darkroom" using chemicals. or in a "lighthroom" using a computer.

Phtoshop is the INDUSTRY STANDARD !

I like the COLOR WHEEL in Painter!

NOW TO MAKE THE MOST gorgeous color images possible.....LEARN...how to use colors & their compliments.... ..in Juxtaposition with one another.

I read those words.. in a book.. in 1970 ...the sentence started with the word LEARN... and this comes with ? PRACTICE.! it took me less than a minute to "remember" those words .. but it took me years how to LEARN how to put them into PRACTICE.

Don't forget that there is a difference between Additive and subtractive. If you use Light then RGB is addative and will give white. But if you use ink that is subtractive and will give black. Hence RGB is usually applied to light sources, and CMYK (Cyan, Magenta, Yellow and Key (Black) is usually applied to inks, dies etc as they are subtractive.
A good base on using coloUr in compositions is a book by Johannes Itten Called the elements of coloUr.

involves the use of Yellow and magenta filters only. cyan is never used for negatives because all it does is increase exposure time due to Netural density.
Subtractvive color printing in a darkroom is the most popular printing method used
I have in my possession Color Separations.. that a newspaper made for some image of mine

they are clear.. transparent. one is cyan or clear the other is yellow or clear the other is magenta or clear.. when all three are combined I see natural colors. from white.. to black just from those three masks.